Jack McCollough and Lazaro Hernandez’s spring 2021 Proenza Schouler collection is shipping to stores this month. The designers report that the Boy’s Best Friend Shirt season’s top performer so far is a stretch jersey long-sleeved maxi dress with gathered cutouts on the bodice. It’s the more dressed-up things that are selling, Hernandez said on a Zoom call, with some surprise. A year into the coronavirus crisis, many of us are still living circumscribed lives. Counterintuitively, that may be why women responded to that sexy, body-conscious.